我刚刚开始使用
Java网络协议.我试图使用我的代理服务器连接到互联网.当我看到’
https://www.tutorialspoint.com/javaexamples/net_poxy.htm‘的帖子时,他们将http.proxyHost属性设置为’proxy.mycompany1.local’.我知道我可以将其设置为我的代理服务器IP,但我很好奇地知道为什么我的程序仍然可以工作,即使我将其设置为一些随机字符串,如“abcd”.
答：“proxy.mycompany1.local”代表什么？
B.我的程序如何工作,即使我将http.proxyHost设置为“abcd”？
以下是我的工作计划：
import java.net.HttpURLConnection;
import java.net.InetSocketAddress;
import java.net.Proxy;
import java.net.ProxySelector;
import java.net.URI;
import java.net.URL;
public class TestProxy {
public static void main(String s[]) throws Exception {
try {
System.setProperty("http.proxyHost","abcd");
System.setProperty("http.proxyPort","8080");
URL u = new URL("http://www.google.com");
HttpURLConnection con = (HttpURLConnection) u.openConnection();
System.out.println(con.getResponseCode() + " : " + con.getResponseMessage());
} catch (Exception e) {
e.printStackTrace();
System.out.println(false);
}
Proxy proxy = (Proxy) ProxySelector.getDefault().select(new URI("http://www.google.com")).iterator().next();
System.out.println("proxy Type : " + proxy.type());
InetSocketAddress addr = (InetSocketAddress) proxy.address();
if (addr == null) {
System.out.println("No Proxy");
} else {
System.out.println("proxy hostname : " + addr.getHostName());
System.out.println("proxy port : " + addr.getPort());
}
}
}
这是输出：
200 : OK proxy Type : HTTP proxy hostname : abcd proxy port : 8080
解决方法
首先,根据
System Properties tutorial.
Warning: Changing system properties is potentially dangerous and
should be done with discretion. Many system properties are not reread
after start-up and are there for informational purposes. Changing some
properties may have unexpected side-effects.
而且我的经验表明,当您更改* .proxyHost属性时,您可能会在系统上收到令人不快的问题.所以我不建议你改变这个任务的系统属性.
更好地使用像：
//Proxy instance,proxy ip = 127.0.0.1 with port 8080
Proxy proxy = new Proxy(Proxy.Type.HTTP,new InetSocketAddress("127.0.0.1",8080));
conn = new URL(urlString).openConnection(proxy);
和代理授权：
Authenticator authenticator = new Authenticator() {
@Override
public PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication("user","mypassword".tocharArray());
}
};
Authenticator.setDefault(authenticator);
现在回到主要问题：
A.“proxy.mycompany1.local”只是例子,你可以使用任何主机名
B.类URL通过Socket使用java.net.PlainSocketImpl类.它尝试解析代理主机名’abcd’,吞下错误并直接转到谷歌.只是试着玩这个代码：
import java.net.*;
import java.io.*;
public class RequestURI {
public static void main(String[] args) {
int port = 8181;
long startTime = System.currentTimeMillis();
try {
// System.getProperties().setProperty("http.proxyHost","abcd");
// System.getProperties().setProperty("http.proxyPort",Integer.toString(port));
URL url = new URL("http://google.com");
HttpURLConnection uc = (HttpURLConnection) url.openConnection();
int resp = uc.getResponseCode();
if (resp != 200) {
throw new RuntimeException("Failed: Fragment is being passed as part of the RequestURI");
}
} catch (IOException e) {
e.printStackTrace();
}
System.out.println("Run time in ms ="+ (System.currentTimeMillis() - startTime));
}
}
